Apparatus for draw-crimping textile strands

ABSTRACT

Draw-crimping apparatus is provided for drawing textile strands to increased length and simultaneously imparting thereto a generally helical crimp or bulky configuration when under relatively low tension. Also so provided is apparatus for uniform heating pretreatment or aftertreatment or both.

United States Patent Inventor Robert K. Stanley Media, Pa.

Nov. 14, 1969 Sept. 7, 1971 Techniservice Corporation Kennett Square, Pa.

Continuation-impart of application Ser. No. 476,933, Aug. 3, 1965, now Patent No. 5 5,

Appl. No. Filed Patented Assignee APPARATUS FOR DRAW-CRIMPING TEXTILE STRANDS 16 Claims, 2 Drawing Figs.

US. Cl

Int. Cl D02q 1/00 [50] Field of Search 28/1 .2, 72.1

[56] References Cited UNITED STATES PATENTS 3,113,366 12/1963 Taylor 28/l.2

Primary ExaminerLouis K. Rimrodt Att0rneyMcClure & Millman ABSTRACT: Draw-crimping apparatus is provided for drawing textile strands to increased length and simultaneously imparting thereto a generally helical crimp or bulky configuration when under relatively low tension. Also so provided is apparatus for uniform heating pretreatment or aftertreatmcnt or both.

PATENTEUSEP new INVENTai, ROBERT K. STANLEY 7: LJuIsu- M m, 477M001,

APPARATUSFOR DRAW-CRIMPING TEXTILESTRANDS This application is a continuation-in-part of my copending application, Ser. No. 476,933 filed Aug. 3, 1965 and now U.S. Pat. No. 3,505,444. Referenceis also made to my copending application, Ser. No. 678,391 filed Dec. 1, 1967 and now Pat. 3,528,148

This invention relates to apparatus for drawing molecularly orientable textile strands to increase. length, and. thereby orienting them, and for crimping such textile strands simultaneously therewith.

Many textile strands, especially those composed of synthetic organic polymers of linear structure, are molecularly orientable by a procedure of extending the strand beyond its elastic limit or fdrawing it, whereupon the strand does not break butattains a stable extended or increased lengthby virtue of longitudinal alignment and possibly slippage of the component polymeric molecules. Such procedureusually involves pulling the strand one or more wrapsabout a solid snubbing surface, most often cylindrical, and frequently involves heating the strand or the snubbing surface or both.

A primary object. of the present invention is provision of crimped strands by means of novel draw-crimping apparatus.

Other objects of thisinvention, together withmeans and methods for attainingthe various objects, willbe apparent from.the following description and theaccompanying diagrams.

FIG. 1 is a representation, partly in elevation and partly in schematic form, of apparatus according to the present invention; and

F IG. 2 is a similar view on a reduced scale, of further apparatus according to this invention, and of crimped strand produced thereby.

In general, the objects ofthe present invention are accomplished, in strand-treating apparatus, by means for pulling a molecularly orientabletextile strand over a snubbing surface to draw it to increased length and, thereby orient it, andmeans for simultaneously cooling the strand while in contact therewith. Upon subsequent relaxation from drawing-tension,

,with or.without the aid of heat, the strand assumes a crimped configuration.

FIG. 1 shows strand ll, of molecularly orientable type, being fed by pair of feed rolls 12, 13 toward the upper right, past heater l4 and to snubbing member 15, which has semicylindrical snubbing surface 16. The strand is pulled past the heater and over the snubbing surface, and thereby extended to increased length (whereupon it is denoted as ll), by pair of draw rolls 17, 18. Block 19 denotes drive means for the rolls by means of suitable drive linkages (indicated in broken lines): 190 to .feed roll 13, 19b to draw roll 17, and 190 to a roll discussed hereinafter. The drive means comprises either an engine or an electric motor (not shown) together with suitable gearing (also not-shown) so that the respective pairs of rolls can be driven at any desired angular speeds and any desired speed ratio. The second roll in each pair may be undriven except by contact with the driven roll and thestrand passing through the roll nip, or both rolls in any pair may be driven alike (but in opposite directions). The draw rolls are driven at a greater surface speed than the feed rolls, preferably several times as great, the actual speed ratio depending upon the drawability of the strand composition and the desired degree of draw to be accomplished. Either or both rolls in each pair may have a resilient surface composed of natural or synthetic elastomeric composition as a deterrent to slipping of the strand thereover, especially at low nip pressures. Godets may replace the illustrated niprolls with like effect.

Snubbing member is provided with conduits 21 and 23, shown with arrows leading respectively to and from the snubbing member, which is hollow (as indicated in broken lines) to interconnect them, and respectively from and to block 25, which represents circulation-inducing means and heat sink. Thus, where the circulating material is a refrigerant fluid, for example, the conduits and the interconnection thereof in the snubbing member comprise the cooling coil, the rest of a conventional refrigerator being represented by block 25, and enlarged portion 22 of the interconnection in the interior of the snubbing member representing a plenum chamber, preferably supplied with fins to the bodyof the member for ready heat-exchange therewith. Alternatively, conduits 21 and 23 may be simply electrical conductors (the arrows representing electrical current flow therein), in which event block 25 represents a DC generator, battery, or equivalent e.m.f. source, and enlarged portion 22 in the snubbing member represents a thermoelectric device (e.g., a Peltier junction or group thereof) adapted to produce a cooling effect upon current flow therethrough in the indicated direction, the'selection of'which is well within the capability of a person skilled in the art.

FIG, 2 shows (on a reduced scale) drawn strand 11 proceeding to the right past heater 27 to pair of strand-forwarding rolls 28, 29 driven through linkage 19c (indicated in broken lines) at a usually intermediate surface speed sufficient to maintain 'in the strand at least some of the tension imparted by the strand-drawing rolls despite any change in length induced by. heater 27 when on. This remaining tension, which may be only sufficient to prevent slack in the strand, 'is released as the roll nip releases the strand (then denoted as 11) into relaxed crimped configuration, which is shown somewhat stylized. If desired, the strand-'forwardingrolls may be omitted and the tension'be released at the nip of the stranddrawing rolls-Also, if desired the strand-feeding rolls may be replaced by equivalent strand-restraining means effective to ensure adequate contact between the strand and the surface of the snubbing member as the strand-drawing rolls pull the strand thereover. The'relaxation step,-which introduces stress relief in the strand, may be repeated, if desired, with or without variation therein.

Use of either or both of heaters 14 and 27 may be dispensed with as may be desired.'Heater 14, which is a preheater to facilitate drawing as is desirable with some strand compositions, may bereplaced upon providing one or both of feed rolls 12, l3 with internal'heating means, such as that shown and described for thefeed rolls of a stuffer crimper in my US. Pat. No. 3,1 1 1,740. Alternatively, with strands of readily drawable compositions, heater 14 "may be removed without such modification of the feed rolls (or simply be left in place but not turned on), as the friction of the strand against snubbing surface l6.and the intermolecular'friction engendered as the strand begins'to draw will induce a heating of the v strand- Of course, the cooledsnubbing member acts-to remove heat of whatever origin from the'drawing or drawn strand; however, unlike the preferred heaters, it does not act uniformly on the strand but contacts it along one side only. Heater 27 is used to heat-relax the drawn strandwherever the latent crimp is -notdeveloped to the extent desired upon 1 simply relaxing the strand by releasing itfrom'tension. Where not required it can be removed or left in place turnedoff. A

heat-relaxation after treatment at a more remote location may be employed instead -of or in addition to heat-relaxation by heater 27. Both heaters 14 and 27 may be of any suitable hollowed if necessary. A semicylindrical snubbing surface is" most convenient, as the strand does not wrap one or more turns about the member as is customary in conventional drawing operations with cylindrical draw pins but passes thereover through a preferred angle of about a radian of arc, or at least about a half radian and at most about two to three radians. Of course, a nonarcuate curved surface may be used, if desired,

whereupon the average (geometric mean) radius of curvature is determinative. In either event the radius of curvature (or average thereof) of the snubbing member should be large with respect to the filamentary diameter of the strand, and for the purposes of this invention large means a minimum ratio of about one hundred times. For most purposes the snubbing member will be selected to have a radius of not less than about 1 centimeter nor more than about 10 centimeters.

The strand may be monofilament or multifilament and may range in size from as small as one or two to fifteen or more denier per filament. In the instance of multifilament strands the total denier may be in the hundreds or even the thousands. The diameter of the largest component filament of multifilament strands should not exceed about one one-hundredth of the radius of curvature of the snubbing surface. In the processing of large bundles of filaments it is preferred to spread them laterally by any suitable means to ensure that the individual filaments are gripped securely by the rolls and are brought into relatively good heat-exchanging relation to the heaters (when used) and the snubbing member. The removal of heat from each filament of the strand by means of the snubbing member during drawing induces a transverse nonuniformity therein, which although only imperfectly understood induces a most satisfactory crimp, the full extent of which becomes apparent only upon subsequent relaxation of the strand, which may be preformed one or more times.

Suitable temperatures or ranges thereof for the snubbing member and the preheater, if used, depend upon the strand composition, period of exposure thereto, and heat-transfer characteristics. For example, an undrawn 6-nylon strand of 4,400 total denier and 68 filaments was fed at 2% meters per minute and drawn at a rate of about l meters per minute (4X draw) without preheating, through slightly more than 30 of are over the surface of a cylindrical snubbing member having a diameter of about centimeters and maintained at a temperature of 20 to 25 C. It is estimated that the drawing momentarily increased the strand temperature to about 65 to 95 C. but that it was reduced by the cool snubbing pin to not more than 40 C. on the side in contact therewith. Upon release of tension the individual filaments in the strand assumed a coiled or curly crimped configuration, which was intensified by aftertreatment at a temperature of about 100 C.

Articles made by knitting, weaving, or otherwise fabricating such strands, with or without addition of other strands or materials, exhibit desirable characteristics of cling, cover, elasticity, and the like. Use of the apparatus of this invention provides such desirable strands by a rapid, readily controlled, and inexpensive technique. Such apparatus may be incorporated readily into the manufacturing line ofa plant in which synthetic strands of molecularly orientable compositions are extruded from melts or solutions thereof.

Although a preferred apparatus embodiment has been illustrated and described, and certain modifications suggested, other modifications may be made therein, as by adding, combing, or subdividing parts, while retaining at least some of the advantages and benefits of the present invention. The invention itselfis defined in the following claims.

The claimed invention:

1. In apparatus for draw-crimping textile strands, the improvement comprising a snubbing member having a curved surface adapted to support a textile strand being drawn in sliding contact thereagainst through an arc of at least one-half radian and at most 3 radians, with means for cooling the curved snubbing surface.

member. 1

4. Strand-crimping apparatus according to claim 1, wherein the snubbing member has a generally semicylindrical snubbing surface.

6. Strand-crimping apparatus according to claim 5, including means downstream from the snubbing member to pullthe strand from a point of final tangency with the snubbing surface thereof intersected by the downstream side of the arc.

7. Strand-crimping apparatus according to claim 5, including means upstream from the snubbing member to restrain the strand passing to a point of initial tangency thereof intersected by the upstream side of the arc.

8. Apparatus for draw-crimping textile strands, comprising strand-restraining means, strand-drawing means, cooled immovable strand-snubbing means intermediate the strandrestraining means and the strand-drawing means, and heating means upstream from the snubbing means and effective to preheat a strand substantially uniformly before passage to the snubbing means.

9. Strand-crimping apparatus according to claim 8, wherein the preheating means is located intermediate the restraining means and the snubbing means.

10. Strand-crimping apparatus according to claim 9, wherein the preheating means comprises a heated enclosure through which the strand travels.

11. Strand-crimping apparatus according to claim I 10, wherein the preheating closure is supplied with steam.

12. Apparatus for draw-crimping textile strands, comprising strand-restraining means, strand-drawing means, cooled immovable strand-snubbing means intermediate the strandrestraining means and the strand-drawing means, and heating means downstream from the snubbing means and effective to reheat substantially uniformly a strand after passage from the snubbing means.

13. Strand-crimping apparatus according to claim 12, wherein the reheating means is located intermediate the snubbing location and strand-forwarding means downstream therefrom.

14. Strand-crimping apparatus according to claim 13, wherein the reheating means comprises a heating enclosure through which the strand travels.

15. Strand-crimping apparatus according to claim 14, wherein the reheating enclosure is supplied with steam.

16. Apparatus for draw-crimping a textile strand, comprising in sequence a pair of strand-feeding rolls, a pair of stranddrawing rolls, and a pair of strand-forwarding rolls, means for rotating the strand-feeding rolls at a given surface speed, means for rotating the strand-drawing rolls at a greater surface speed, means for rotating the strand-forwarding rolls at an intermediate speed, and a cooled heat-conductive strandsnubbing member located intermediate the first two pairs of rolls and in the strand path therebetween and having a fixed snubbing surface adapted to receive a strand in snubbing contact therewith. 

2. Strand-crimping apparatus according to claim 1, wherein the snubbing member is hollowed to receive cooling means.
 3. Strand-crimping apparatus according to claim 2, wherein the cooling means comprises a refrigerant fluid and means to circulate it in heat-exchanging relationship with the snubbing member.
 4. Strand-crimping apparatus according to claim 2, wherein the cooling means comprises a thermoelectric junction located in heat-exchanging relationship with the snubbing member.
 4. Strand-crimping apparatus according to claim 1, wherein the snubbing member has a generally semicylindrical snubbing surface.
 6. Strand-crimping apparatus according to claim 5, including means downstream from the snubbing member to pull the strand from a point of final tangency with the snubbing surface thereof intersected by the downstream side of the arc.
 7. Strand-crimping apparatus according to claim 5, including means upstream from the snubbing member to restrain the strand passing to a point of initial tangency thereof intersected by the upstream side of the arc.
 8. Apparatus for draw-crimping textile strands, comprising strand-restraining means, strand-drawing means, cooled immovable strand-snubbing means intermediate the strand-restraining means and the strand-drawing means, and heating means upstream from the snubbing means and effective to preheat a strand substantially uniformly before passage to the snubbing means.
 9. Strand-crimping apparatus according to claim 8, wherein the preheating means is located intermediate the restraining means and the snubbing means.
 10. Strand-crimping apparatus according to claim 9, wherein the preheating means comprises a heated enclosure through which the strand travels.
 11. Strand-crimping apparatus according to claim 10, wherein the preheating closure is supplied with steam.
 12. Apparatus for draw-crimping textile strands, comprising strand-restraining means, strand-drawing means, cooled immovable strand-snubbing means intermediate the strand-restraining means and the strand-drawing means, and heating means downstream from the snubbing means and effective to reheat substantially uniformly a strand after passage from the snubbing means.
 13. Strand-crimping apparatus according to claim 12, wherein the reheating means is located intermediate the snubbing location and strand-forwarding means downstream therefrom.
 14. Strand-crimping apparatus according to claim 13, wherein the reheating means comprises a heating enclosure through which the strand travels.
 15. Strand-crimping apparatus according to claim 14, wherein the reheating enclosure is supplied with steam.
 16. Apparatus for draw-crimping a textile strand, comprising in sequence a pair of strand-feeding rolls, a pair of strand-drawing rolls, and a pair of strand-forwarding rolls, means for rotating the strand-feeding rolls at a given surface speed, means for rotating the strand-drawing rolls at a greater surface speed, means for rotating the strand-forwarding rolls at an intermediate speed, and a Cooled heat-conductive strand-snubbing member located intermediate the first two pairs of rolls and in the strand path therebetween and having a fixed snubbing surface adapted to receive a strand in snubbing contact therewith. 